1. Field of the Invention
The present invention relates in one aspect to a purification apparatus and method for processing a plurality of fluid samples of biological material. In a particular embodiment, this invention relates to a purification apparatus for filtering fluid samples through filters of a purification tray into the sample wells of a sample well tray in a manner that minimizes the risk of cross-contamination between adjacent sample wells.
2. Description of the Related Art
Biological testing using sample trays with a plurality of sample wells has become increasingly popular in recent years. Biological testing of samples in an array of wells is utilized in a wide variety of applications such as genome sequencing, drug discovery, and disease detection and monitoring. In typical applications, it is desirable to process the biological sample through a filter prior to placing the biological sample in the sample wells. A purification tray is typically provided for processing the biological samples.
For example, in one particular process used to prepare RNA, a biological sample which has undergone sample preparation steps is placed in the columns of a purification tray. A series of washes are performed to remove any remaining DNA and cellular debris from the filter elements that may inhibit the later reaction. As a result, RNA is trapped on filter material located in the columns. Next, with a sample well tray positioned immediately below the purification tray, an elution solution is dropped into the columns so that the purified RNA solubilizes and leaves the filter to be discharged into the sample wells of the sample well tray. The sample well trays with the purified RNA may then undergo any suitable thermal or chemical operation.
During the process of discharging the biological sample into the sample wells, aerosols are typically created in and above the sample wells. In a typical system for processing a biological sample, a purification tray is placed immediately on top of the well tray. During the process of drawing the solution through the filters and into the sample wells, aerosols are typically formed in the sample wells and in the region between the sample well tray and the purification tray. Existing devices are inadequate in removing the aerosols from the sample wells without cross-contamination occurring between adjacent sample wells. This type of cross-contamination adversely affects the accuracy and effectiveness of the later operations.
It is desirable to provide a purification apparatus for processing a plurality of fluid samples that reduces the amount of cross-contamination between wells. In addition, it is particularly desirable to provide such an apparatus that is suitable for use at higher temperatures.
The advantages and purposes of the invention will be set forth in part in the description which follows, and in part will be apparent from the description, or may be appreciated by practice of the invention. The advantages and purposes of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
In one aspect, the invention includes a filtration apparatus for processing a plurality of fluid samples. The filtration apparatus includes a purification tray and a sample well tray. The purification tray includes a filter plate, a plurality of filters and a plate including flow obstructions. The filter plate has a plurality of columns with a discharge opening at the bottom of each column. The plurality of filters align with the columns of the filter plate. The sample well tray has a plurality of sample wells aligned with the columns of the filter plate for receiving fluid from the discharge openings. The vent plate is positioned in a space between the filter plate and the sample well tray. The vent plate flow obstructions are positioned adjacent the sample wells in order to limit cross-contamination between sample wells. The flow obstructions define at least one discrete flow path for permitting aerosols from a sample well to pass therethrough out of the respective sample well while preventing the aerosols from contaminating adjacent sample wells. In one embodiment, the purification tray further includes a heat transfer plate positioned between at least a portion of the filter plate and at least a portion of the vent plate. In another embodiment, the sample well tray includes a removal mechanism for assisting in the removal of the sample well tray.
In another aspect, the invention includes a purification tray for processing a plurality of fluid samples into sample wells. The purification tray includes a filter plate having a plurality of columns with discharge openings at the bottom thereof, at least one filter positioned in the columns of the filter plate for filtering the fluid samples as they pass therethrough, a vent plate positioned between the filter plate and the sample wells, and a heat transfer plate. The vent plate includes vents for permitting aerosols from the sample wells to escape, while preventing the aerosols from contaminating sample wells. The heat transfer plate is positioned between the vent plate and a portion of the filter plate and is configured to transfer heat to the fluids in the columns of the filter plate. In a further aspect of the invention, the invention includes a filling apparatus for filling sample wells with a liquid sample. The filling apparatus includes a filling plate, a heat transfer plate, an aerosol guard, and a sample tray. The filling plate has a plurality of filling columns having discharge openings adjacent the bottom thereof through which a liquid sample may exit the filling column to flow into a sample well. The heat transfer plate transfers heat to the filling columns of the filling plate and is in contact with the filling plate. The aerosol guard is attached to a surface of the heat transfer plate, and includes a plate with a plurality of passages for the flow of aerosols therethrough. The sample tray includes a plurality of sample wells for receiving liquid sample from at least one of the discharge openings of the filling plate and is positioned with respect to the aerosol guard to permit aerosols in the sample wells to exit from the sample wells through apertures in the aerosol guard.
In a yet further aspect of the invention, the invention includes an aerosol guard for directing aerosols formed in sample wells away from the sample wells. The aerosol guard includes a plate of substantially non-porous material and a plurality of raised surfaces on a first side of the plate. The raised surfaces direct aerosols from sample wells to flow through the aerosol guard. The raised surfaces are positioned around corresponding sample wells to inhibit cross-contamination between sample wells.
In another aspect, the present invention is directed toward a method of filtering liquid samples into sample wells in a sample well tray using a purification tray. The method includes providing a purification tray and sample well tray. The purification tray has a plurality of columns with discharge openings at the bottom thereof. The method further includes providing filters in the plurality of columns, introducing a liquid sample into at least one column of the purification tray so that the liquid sample contacts the filter in the column, applying a pressure differential to the column so that the liquid sample is urged through the filter and out of a discharge opening of the column into the sample well, and obstructing aerosols formed in the sample wells from mixing with the liquid sample of an adjacent sample well by providing an aerosol guard with a discrete flow path out of the sample well.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.